HL 2 December 2024 Biology Past Paper PDF

Study Guide for SL/HL 2 December 2024 This is a guide to help you prepare for the exam. Please Study and review your past worksheets and notes. 1. Which ecological level involves biotic factors but not abiotic factors? a. Community b. Ecosystem c....

Study Guide for SL/HL 2 December 2024 This is a guide to help you prepare for the exam. Please Study and review your past worksheets and notes. 1. Which ecological level involves biotic factors but not abiotic factors? a. Community b. Ecosystem c. Population d. Both A and C 2. What best defines the concept of carrying capacity? a. The number of species an environment can support b. The minimum population a species can maintain c. The maximum population a species can sustain d. The total individual count of all species in an area 3. Which example shows negative feedback in regulating population size? a. Predators bringing prey population back to carrying capacity b. An increase in prey leading to fewer predators c. Changes in environmental factors that do not depend on population density d. Exponential population growth 4. What defines an alien species? a. A species introduced to an area by human action b. A species with widespread geographical distribution c. A species not yet discovered by scientists d. A harmful or pathogenic species 5. How would an ecologist use a quadrant in their research? a. Estimate animal immigration and emigration b. Measure plant population sizes by sampling c. Trap and mark animals for release d. Measure light intensity based on the Sun's position 6. What statistical test would help determine if two species of limpets occur together by chance or due to interaction?  a. Chi-squared test b. T-test c. Standard deviation d. Means and ranges Cellular Respiration and Metabolism 7. Which products are common to both anaerobic and aerobic respiration in humans? a. Pyruvate b. ATP c. Lactate d. Pyruvate and ATP 8. What is the net ATP yield from glycolysis for each molecule of glucose? a. 2 b. 4 c. 10 d. 38 9. In the mitochondria, how do protons flow during ATP synthesis? a. From the matrix to the intermembrane space b. From the intermembrane space to the matrix c. From the intermembrane space to the cytoplasm d. From the cytoplasm to the intermembrane space 10. What occurs during the link reaction in aerobic respiration? a. NAD+ is reduced b. Pyruvate undergoes decarboxylation c. It occurs in the cytoplasm d.. FAD+ is reduced 11. What happens during glycolysis when a hexose sugar is broken down? a. Phosphorylation → oxidation → lysis b. Oxidative → phosphorylation → lysis  c. Phosphorylation → lysis → oxidation d. Lysis → oxidation → phosphorylation 12. Which process directly generates ATP in mitochondria? a. Proton movement from the matrix to the intermembrane space b. Proton movement from the intermembrane space to the matrix c. Splitting of water and electron transfer to oxygen d. Proton movement from the intermembrane space to the cytoplasm Enzymes and Biochemical Reactions 13. How do enzymes influence activation energy? a. Lower the energy required for reaction initiation b. Increase the energy required for the reaction c. Alter the shape of the active site d. Stabilize the reaction pathway 14. What is the effect of a competitive inhibitor on enzyme activity? a. Decreases reaction temperature b. Increases substrate concentration c. Enhances the activity of the enzyme d. Increases the temperature at which the reaction occurs 15. Which describes the induced-fit model of enzyme binding? a. The substrate and active site are complementary in shape b. Both the enzyme and substrate undergo conformational changes c. Enzymes bind to a specific substrate d. Enzymes can be immobilized 16. What happens in feedback inhibition? a. Changes in transpeptidases lead to antibiotic resistance b. The pathway that produces isoleucine is regulated c. The use of statins to control cholesterol is an example d. The Calvin cycle is regulated Photosynthesis and Plant Biology 17. Where is chlorophyll located within plant cells? a. Thylakoid membranes b. Stroma c. Mitochondrial matrix d. Cristae 18. What is produced by the light-dependent reactions of photosynthesis that is later used in the Calvin cycle? a. Hydrogen and oxygen b. ATP and NADPH c. NADPH and oxygen d. ATP and CO2 19. What occurs in the light-independent reactions of photosynthesis? a. Water molecules are split b. ATP is synthesized c. NADP is reduced d. CO2 is reduced 20. Which molecule is the first identifiable product after carbon fixation in photosynthesis? a. Ribulose bisphosphate (RuBP) b. Glycerate-3-phosphate (GP) c. Triose phosphate (TP) d. Acetyl CoA 21. What is the function of thylakoid membranes in the chloroplasts? a. They create a high concentration of protons for ATP production b. They concentrate photosynthetic pigments c. They provide a surface for the Calvin cycle enzymes d. They produce ATP and NADPH Nerve Function and Action Potentials 22. Which ion movement triggers an action potential in a neuron? a. Calcium b. Magnesium c. Sodium d. Potassium 23. What happens after the highest point of the action potential in a nerve impulse? a. Sodium channels open, and Na+ enters the neuron b. Sodium channels open, and Na+ exits the neuron c. Potassium channels open, and K+ exits the neuron d. Potassium channels open, and K+ enters the neuron 24. During synaptic transmission, what happens to calcium ions? a. They enter the synaptic knob from the synaptic cleft b. They enter the postsynaptic neuron from the cleft c. They leave the synaptic knob into the synaptic cleft d. They leave the postsynaptic neuron into the synaptic cleft 25. What restores the resting potential of a neuron after depolarization? a. Sodium ions diffuse out of the neuron b. Potassium ions diffuse into the neuron c. Potassium ions diffuse out of the neuron d. Sodium ions diffuse into the neuron Immunology and Hormonal Control 26. Which cells are primarily responsible for secondary immune responses? a. Cytotoxic T-cells b. Phagocytes c. Memory cells d. Macrophages 27. Which of the following describes the role of oxytocin?  a. Stimulates uterine contractions b. Controls fetal brain development c. Initiates ovulation d. Supports blastocyst implantation 28. What causes glucagon secretion to increase?* a. Fasting for a long period b. After a carbohydrate-rich meal c. During physical rest d. When body temperature drops 29. Which cells are responsible for destroying virus-infected body cells? a. Activated B-cells b. Cytotoxic T-cells c. Plasma cells formed by clonal selection d. Phagocytic macrophages 30. Which part of the immune system helps fight bacterial infections? a. Antigen presentation by macrophages b. Activation of helper T-cells c. Activation of B-cells d. All of the above in sequence 31. Know how to label mitochondria chloroplast, and the human brain  32. Explain the process of aerobic respiration including oxidative phosphorylation. There are 4 stages in this process. First, glycolysis, second, link reaction, third krebs cycle, and fourth oxidative phosphorylation. 1. Glycolysis is the first step of cellular respiration and occurs in the cytoplasm/cytosol. Glucose is a 6-carbon sugar and it undergoes phosphorylation using 2 atp molecules, resulting in the formation of fructose 1-6 phosphate. This 6-carbon molecule is split into 3-carbon molecules of glyceraldehyde 3 phosphate (G3P). After that reaction the G3P is converted into pyruvate which generates 2 NADH and 2 ATP.  2. Second is the link reaction pyruvate enters the mitochondria. Pyruvate is decarboxylated, it loses 1 carbon then it combines with coenzyme A which forms Acetyl-coa. NADH is also produced from this process. 3. The third stage of aerobic respiration is the Krebs cycle. Acetyl-coa enters the krebs cycle in the mitochondrial matrix then it goes back to the link reaction. The 2-carbon acetyl group combines with a 4 carbon molecule to form a 6 carbon molecule. In this cycle the 1 carbon goes through several transformations, it produces 1 ATP, 2Co2, 3 NADP+, FADH, and 2CO2 (waste). One is produced each cycle which doubles the products. This happens twice because the Acetyl-coa molecule was entered through the cycle for each glucose, it is doubled. 4. The last stage is oxidative phosphorylation the NADH and FADH that were produced during glycolysis, the link reaction, and the krebs cycle, gives electrons to the electron transport chain(ETC) protons H+ which are pumped from the mitochondrial matrix into the inner membrane space which after makes a proton gradient. The protons flow back into the matrix and are called chemiosmosis. At the end of the ETC, oxygen accepts electrons and it combines with protons in order to form water. The total ATP produced from oxidative phosphorylation is 34 ATP per glucose molecule. 33. Explain how vaccination works in terms of immunological memory and herd immunity Vaccination works by introducing a pathogen such as a n inactivated virus or a piece of its genetic material to stimulate The immune system without causing disease. This exposure prompts the body to produce antibodies and memory cells which remember the pathogen so the immunity system can respond more quickly and effectively. vaccination also contributes to her immunity when a large percentage of the population becomes immune either through vaccination or prior infection the spread of disease is limited protecting those who cannot be vaccinated or who have weaker immune responses. 34. Know how to draw and label a graph showing the sigmoid (S-shaped) population growth curve 35. Know how to label a motor neuron and explain how a nerve impulse travels along a neuron. a. The sodium potassium pump maintains a resting potential. It expels 3 sodium per 2 potassium admitted (active transport) This results in a negative membrane potential (roughly -70). b. Sodium channels open in response to signal of receptor/dendrite there is a passive influx of sodium ions to cause depolarization c. Potassium channels open in response to depolarization there is a passive efflux of potassium ions (repolarization)  d. There is a length of time needed before the neuron re-fires. During this refractory period the resting potential is re-established by the sodium potassium pump. 36. Know how to label the Synapse diagram a. Action potential (pre-synaptic) b. Calcium channels c. Vesicles d. Receptors e. Neurotransmitters f. Action potential (post- Synaptic) g. Synapse 37. Chi-Square practice question. 2 The presence or absence of two species of scallop was recorded in fifty quadrats (1m ) on a rocky seashore The following distribution pattern was observed: 6 quadrats = both species ; 15 quadrats = king scallop only ; 20 quadrats = queen scallop only ; 9 quadrats = neither species Is there an association between the two species?